Active capacitive stylus, sensor controller, related system and method

ABSTRACT

A method may be executed by one or more active capacitive styluses and a sensor controller connected to sensor electrodes. The method includes: a discovery step, executed by the sensor controller, of repeatedly sending out a discovery packet for detecting any of the active capacitive styluses; a discovery response step, executed by a first active capacitive stylus among the one or more active capacitive styluses, by which the discovery packet is detected, of returning a response packet to the discovery packet; a configuration step, executed by the sensor controller, of transmitting a configuration packet including time slot designation information that designates a first time slot to the first active capacitive stylus; and a data transmission step, executed by the first active capacitive stylus, of transmitting operation state data indicative of an operation state of the first active capacitive stylus using the designated first time slot.

BACKGROUND Technical Field

The present invention relates to an active capacitive stylus, a sensorcontroller, a system including an active capacitive stylus and a sensorcontroller, and a method executed by an active capacitive stylus, asensor controller and a system. In particular, the present inventionrelates to an active capacitive stylus, a sensor controller and a systemincluding them, which are suitable where one or more active capacitivestyluses are operated to repeatedly move into and out of a detectionrange of sensor electrodes and methods executed by the active capacitivestylus, the sensor controller and the system.

Description of the Related Art

Styluses of various types having a pen shape have become available foruse as an inputting device, for handwritten input on a panel of anelectronic apparatus. A stylus called an active capacitive stylusincludes an oscillation circuit, which sends out a frequency signal tocause an electrode provided near a tip end of the stylus to generate avariation of an electric field (alternating electric field) at a pointedposition near the tip end of the stylus. A sensor provided in theelectronic apparatus uses a group of electrodes disposed in a matrixform, to detect a variation of the charge amount induced in theelectrode group by the variation of the electric field, to therebydetect a signal from the stylus. The position pointed by the stylus isderived based on the position of the electrode at which the signal isdetected, the level of the detected signal, and so forth.

Among active capacitive styluses, some styluses can transmit informationto a sensor controller by modulating a signal supplied from theoscillation circuit with information, such as pen pressure and a uniquepen identification (ID).

An electronic pen disclosed in PCT Patent Publication No. WO2015/111159(hereinafter, referred to as Patent Document 1) is an example of anactive capacitive stylus of the type capable of transmittinginformation. The electronic pen successively transmits a continuoussignal CS for position detection, and a signal block SIB including afirst modulated signal obtained by modulating the continuous signal CSwith partial information, which is obtained by dividing firstinformation (a unique ID or the like associated with the electronicpen), to the position detection apparatus.

FIG. 14A depicts an example of a transmission signal including thecontinuous signal CS and the signal block SIB. FIG. 14B shows that thefirst information is transmitted by a plurality of signal blocks SIB. InFIG. 14B, a division number (block number A, B, . . . , n) represents anumber of an ID block corresponding to partial information. Amicroprocessor of a tablet in Patent Document 1 is configured to outputposition information, which is obtained from the continuous signal CS,and the first information in an associated relationship with each other.

Communication between an active capacitive stylus and a sensorcontroller is implemented by a local alternating electric field in theproximity (within approximately several millimeters to several tens ofmillimeters) of a pen tip electrode. Since communication that uses anelectric field exhibits large attenuation in signal level depending onthe distance, such communication is interrupted every time the stylus ismoved away from the sensor of the electronic apparatus. Therefore,unlike wireless communications such as Bluetooth® communications, thestylus-sensor controller communication is not performed continuously.

Further, even if the stylus and the sensor have a proximate positionalrelationship with each other, the communication speed is rather limited.

Accordingly, it is desirable to minimize communication resources, suchas time and frequency resources, needed for the stylus to communicateconfiguration data indicative of a stylus function or a stylus ID thatdo not vary depending on an operation state of the stylus to the sensor.

It would be desirable to provide technical support for: (1) a usageform, in which a user repeats a cycle of moving down a certain stylus,moving the stylus horizontally by a certain distance and then moving upthe stylus, to thereby repeat the movement cycle into and out of adetection range of one sensor controller, and (2) another usage form, inwhich the user alternately uses a first stylus and a second stylus,while the first stylus and the second stylus are distinguishable fromeach other and while reducing the number of times data, which do notvary depending upon an operation state of the stylus (such as a stylusidentifier), needs to be communicated from each stylus to the sensor.

BRIEF SUMMARY

According to a first aspect of the present invention, there is provideda method executed by one or more active capacitive styluses and a sensorcontroller connected to sensor electrodes. The method includes adiscovery step, executed by the sensor controller, of repeatedly sendinga discovery packet to detect any active capacitive stylus that may bepresent. The method further includes a discovery response step, executedby a first active capacitive stylus which has detected the discoverypacket, from among the one or more active capacitive styluses, ofreturning a response packet. The method further includes a configurationstep, executed by the sensor controller, of transmitting a configurationpacket including time slot designation information that designates afirst time slot to the first active capacitive stylus. The method alsoincludes a data transmission step, executed by the first activecapacitive stylus, of transmitting operation state data indicative of anoperation state of the first active capacitive stylus using the firsttime slot designated by the configuration packet.

According to a second aspect of the present invention, the methodincludes a configuration information request step, executed by thesensor controller, of transmitting, to the first active capacitivestylus, a configuration information request packet that requestsconfiguration information of the first active capacitive stylus, and aconfiguration response step, executed by the first active capacitivestylus, of transmitting the configuration information in response toreceiving the configuration information request packet. The sensorcontroller transmits the configuration packet after receiving theconfiguration information from the first active capacitive stylus. Theconfiguration information includes, for example, a first stylusidentifier which is prestored in the first active capacitive stylus.

According to another aspect of the present invention, there is provideda system including one or more active capacitive styluses, and a sensorcontroller connected to sensor electrodes. The sensor controllerrepeatedly sends a discovery packet to detect any of the activecapacitive styluses. The sensor controller transmits, to an activecapacitive stylus among the one or more active capacitive styluses andfrom which a response packet to the discovery packet is received, aconfiguration packet including time slot designation information. Thetime slot designation information defines time slots, which use thediscovery packet as a timing reference. Any of the one or more activecapacitive styluses returns the response packet when the activecapacitive stylus detects the discovery packet, and transmits operationstate data indicative of an operation state of the active capacitivestylus using the time slots designated by the configuration packet.

According to a further aspect of the present invention, there isprovided an active capacitive stylus for use with a system, whichincludes one or more active capacitive styluses and a sensor controllerconnected to sensor electrodes. The sensor controller repeatedly sendsout a discovery packet to detect any of the active capacitive stylusesand transmits, to an active capacitive stylus among the one or moreactive capacity styluses and from which a response packet to thediscovery packet is received, a configuration packet including time slotdesignation information. The time slot designation information definestime slots, which use the discovery packet as a timing reference. Theactive capacitive stylus returns the response packet when the discoverypacket is detected, and transmits operation state data indicative of anoperation state of the active capacitive stylus using the time slotsdesignated by the configuration packet, from among time slots defined bythe reference timing.

According to a still further aspect of the present invention, there isprovided a sensor controller for use with a system which includes one ormore active capacitive styluses and the sensor controller connected tosensor electrodes. Any of the one or more active capacitive styluses isoperable to return, when the active capacitive stylus detects adiscovery packet for detecting the active capacitive stylus, a responsepacket, and to transmit operation state data indicative of an operationstate of the active capacitive stylus using time slots designated by aconfiguration packet including time slot designation information fordesignating time slots, which use the discovery packet as a timingreference. The sensor controller repeatedly sends out the discoverypacket and transmits the configuration packet to any of the one or moreactive capacitive styluses, from which the response packet to thediscovery packet is returned.

According to the first aspect of the present invention, the sensorcontroller can identify a first active capacitive stylus based on afirst time slot designated by a configuration packet. Even when a stylusidentifier is not added to operation state data, the sensor controllercan recognize, from the fact that the operation state data is receivedin the first time slot, that the operation state data has beentransmitted from the first active capacitive stylus. Accordingly, whenthe first active capacitive stylus transmits operation state data, itcan omit transmission of the stylus identifier.

According to the second aspect of the present invention, the sensorcontroller can acquire, via wireless communication, a first stylusidentifier from the first active capacitive stylus, and associate thefirst stylus identifier with a communication channel, which is used forcommunication with the first active capacitive stylus, in acommunication resource table. Accordingly, even if a stylus identifieris not added to the operation state data, the sensor controller canoutput the received operation state data in association with the firststylus identifier to a host controller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a position inputting system;

FIG. 2 is a functional block diagram of a stylus;

FIG. 3 is a functional block diagram of a sensor controller;

FIGS. 4A to 4D are views illustrating four different operation modes;

FIGS. 5A and 5B are views depicting a common format for various packets;

FIGS. 6A to 6D are views illustrating packets communicated in the fouroperation modes;

FIGS. 7A to 7D are views illustrating communication channels;

FIG. 8 is a view depicting a communication resource table;

FIG. 9 is an operation flow diagram of the sensor controller,particularly of a stylus detection unit;

FIG. 10 is an operation flow diagram of the stylus, particularly of acommunication controlling unit;

FIG. 11 is a view illustrating an example of operation, in which a firststylus repeats moving into and out of a detection range of the sensorcontroller;

FIG. 12 is a view illustrating another example of operation, in whichthe first stylus and a second stylus are alternately used;

FIG. 13 is a modification to the operation flow diagram of the sensorcontroller, particularly, of the stylus detection unit;

FIG. 14A is a view illustrating an example of a transmission signal fromthe electronic pen disclosed in Patent Document 1; and

FIG. 14B is a view illustrating a transmission method of firstinformation by the electronic pen disclosed in Patent Document 1.

DETAILED DESCRIPTION

In the following, exemplary embodiments of the present invention aredescribed with reference to the accompanying drawings.

FIG. 1 is a schematic view of a position inputting system 1 according toone embodiment. Referring to FIG. 1 , the position inputting system 1includes styluses 100 for each pointing to a position, and a sensorcontroller 200 for deriving a position pointed to by each of thestyluses 100 using sensor electrodes 201. The styluses 100 include afirst stylus 101 and a second stylus 102, both of which are configuredas an active capacitive stylus. As used herein, the stylus 100 meanseither of the first stylus 101 or the second stylus 102 and is used as ageneric term to refer to an unspecified stylus.

-   -   (1) In a first usage form, a user may use the first stylus 101        to move it down, move it horizontally for some time to draw a        trace st1 in FIG. 1 , and then move it up. Thereafter, the user        may resume use of the first stylus 101 by moving it down, moving        it horizontally for some time to draw a different trace st2, and        then moving it up. When the user repeats the cycle from the        moving down operation to the moving up operation of the first        stylus 101, the first stylus 101 repeats movement of the first        stylus 101 into and out of a detection range of the single        sensor controller 200.    -   (2) In a second usage form, the user may set aside the first        stylus 101 that the user has been using on the sensor, and then        picks up to use the second stylus 102 in place of the first        stylus 101, wherein the second stylus 102 has different settings        (e.g., type/style of brush) from those of the first stylus 101.        In this case, the first stylus 101 and the second stylus 102        alternately repeat movement into and out of the detection range        of the single sensor controller 200. In FIG. 1 , a trace st3        indicates a trace inputted by the second stylus 102 having        settings different from those of the first stylus 101.

Broken line circles P1 and P2 in FIG. 1 indicate positions pointed to bythe first stylus 101 and the second stylus 102, respectively. An arrow“DS” in the proximity of the broken line circle P1 indicates a downlinksignal DS, which is a signal transmitted in a direction from the firststylus 101 to the sensor controller 200. Another arrow “US” in theproximity of the broken line circle P2 indicates an uplink signal US,which is a signal transmitted in a direction from the sensor controller200 to the second stylus 102.

The sensor controller 200 uses the downlink signal DS and the uplinksignal US to perform bidirectional communication with one or morestyluses 100 placed on the sensor electrodes 201. Further, the sensorcontroller 200 performs a process of supplying the pointed positions ofthe first stylus 101 and the second stylus 102, while distinguishing thestyluses from each other, to an electronic apparatus controlling unit300 (host controller), which controls an electronic apparatus 301 as awhole.

FIG. 2 is a functional block diagram of the stylus 100. Referring toFIG. 2 , the stylus 100 includes an electrode 103, atransmission-reception switching unit 104, an oscillation unit 111, atransmission unit 112, a reception unit 113, an operation informationdetection unit 117, an operation inputting unit 118, a configurationinformation retaining unit, and a communication controlling unit 120.

The electrode 103 is a conductor, which generates an alternatingelectric field corresponding to a downlink signal DS supplied from thetransmission-reception switching unit 104. The electrode 103 alsogenerates a charge corresponding to the uplink signal US and suppliesthe charge to the transmission-reception switching unit 104. These twooperations are alternately performed.

The transmission-reception switching unit 104 switches the connectionstate of the electrode 103 between being connected to the transmissionunit 112, or to the reception unit 113, in response to a switchingsignal S_Sel. The transmission-reception switching unit 104 performstime division switching between transmission and reception within onetime slot s, or in the unit of multiple time slots s.

The oscillation unit 111 is an oscillation circuit that generates asignal of a sine wave or a corresponding rectangular wave of one offrequencies f0, f1, f2, . . . (see FIGS. 7A to 7D) in response to afrequency setting signal F_Sel.

The transmission unit 112 generates a downlink signal DS correspondingto a packet to be transmitted (e.g., a discovery response packet D_DP,an operation state transmission packet OD_DP, or an configurationinformation transmission packet CD_DP) supplied thereto from thecommunication controlling unit 120. For example, the transmission unit112 generates a downlink signal DS corresponding to each type of packet,by adding an error detection code and so forth to a bit trainconfiguring a packet to generate a transmission digital signal,digital-to-analog (DA) converting the transmission digital signal toobtain a baseband signal, and modulating a frequency f (f0, f1, f2, . .. ) provided thereto from the oscillation unit 111 with the basebandsignal.

The reception unit 113 extracts a packet from the uplink signal US andsupplies the extracted packet to the communication controlling unit 120.For example, the reception unit 113 receives the uplink signal US basedon a variation of the charge amount induced in the electrode 103,demodulates (extracts) the baseband signal from the received uplinksignal US using the signal of the frequency f provided from theoscillation unit 111, AD converts the baseband signal to obtain areception digital signal, and uses a value of a local identifier LID (tobe described later) to extract a packet that is addressed (directed) tothe stylus itself (e.g., a discovery packet D_UP, a configurationinformation request packet CD_UP, a channel change request packet CC_UP,or an operation state request packet OD_UP). Further, the reception unit113 uses a synchronizing code (see FIG. 6A) included in the discoverypacket D_UP transmitted at the beginning of a predetermined period T(see FIGS. 7A to 7D) to detect start timing of a frame corresponding tothe predetermined period T.

The operation information detection unit 117 acquires and outputsoperation state data OD, which is information that varies in response toan operation state of the stylus 100, such as an on/off operation of theoperation inputting unit 118 (e.g., a button provided on the stylus100), the value of pen pressure F detected by a pen pressure detectionunit (not depicted), and a remaining amount of a battery charge.

The configuration information retaining unit 119 retains configurationdata CD, which is static data that does not vary in response to anoperation state of the stylus 100 (as opposed to data that varies inresponse to an operation state of the stylus 100, such as the positionof the stylus, a pen pressure applied to the tip of the stylus, andwhether or not a button is depressed). The configuration data CDincludes, for example, a stylus identifier SID uniquely assigned to eachstylus 100, a vendor ID indicative of a manufacturer of the stylus 100,and function information indicative of functions of the stylus 100(e.g., type of the pen point, a brush type, a number of buttons, etc.).

The communication controlling unit 120 utilizes the functional unitsdescribed above to transmit and receive various packets depicted inFIGS. 6A to 6D, to and from the sensor controller 200, using acommunication channel set in the communication setting table to therebyexecute a position inputting method shown in a flow chart of FIG. 10 .

FIG. 3 is a functional block diagram of the sensor controller 200 usedtogether with the sensor electrodes 201.

The sensor electrodes 201 include a row electrode group 202 includingrow electrodes 202 a, 202 b and 202 c and a column electrode group 203including column electrodes 203 a, 203 b, 203 c and 203 d, which aredisposed two-dimensionally so as to form a plane parallel to a panel ofthe electronic apparatus 301.

A transmission-reception switching unit 204 is a switch fortime-divisionally switching between a transmission time period, withinwhich the row electrode group 202 is used as transmission electrodes,and a reception time period, within which the row electrode group 202 isused as reception electrodes. In a time period within which a signalfrom the stylus 100 is received, both of the row electrode group 202 andthe column electrode group 203 are used as reception electrodes. In atime period within which a signal is transmitted to the stylus 100, therow electrode group 202 is used as transmission electrodes.

The sensor controller 200 includes a transmission unit 211, anoscillation unit 212, a reception unit 213, and a stylus detection unit215. The sensor controller 200 is connected to the row electrode group202 through the transmission-reception switching unit 204 and isconnected directly to the column electrode group 203.

The oscillation unit 212 generates a signal of a sine wave, or arectangular wave, of a frequency f, which is one of the frequencies f0,f1, f2, . . . (see FIGS. 7B and 7C), in response to the frequencysetting signal F_Sel.

The transmission unit 211 generates an uplink signal US corresponding toany of various packets (e.g., a discovery packet D_UP, a configurationinformation request packet CD_UP, a channel change request packet CC_UP,and an operation state request packet OD_UP) supplied from the stylusdetection unit 215. For example, the transmission unit 211 performs anencoding process including an error correction process, such as to add arepetition code to a bit train configuring a packet, to generate atransmission digital signal. The transmission unit 211 then DA convertsthe transmission digital signal to obtain a baseband signal, andmodulates a (carrier) signal of the frequency f (f0, f1, f2, . . . )supplied from the oscillation unit 212 by the baseband signal togenerate an uplink signal US. The uplink signal US is transmitted fromthe entire area of the panel, including regions in the proximity of thecircles P1 and P2, so that not only a stylus 100 whose position is knownalready but also a new stylus 100 whose position is not yet known can bedetected.

The reception unit 213 receives a downlink signal DS as an input andoutputs a packet extracted from the received downlink signal DS. Forexample, the reception unit 213 multiplies the downlink signal DS, whichis a modulated signal, by a carrier signal supplied from the oscillationunit 212 to demodulate (extract) the baseband signal. The reception unit213 AD converts the demodulated baseband signal to obtain a receptiondigital signal and performs error correction and so forth to extract apacket. At the same time, the reception unit 213 supplies positioninformation Pos representative of an electrode, at which the downlinksignal DS corresponding to the packet is received, to the stylusdetection unit 215.

The stylus detection unit 215 executes a position inputting methoddepicted in the flow chart of FIG. 9 using the functional unitsdescribed hereinabove. For example, the stylus detection unit 215stores, as an entry in a communication resource table CRTbl, arelationship between a communication channel allocated to a stylus 100and configuration data CD of the stylus 100. The stylus detection unit215 and the stylus 100 use the allocated communication channel toperform transmission and reception of various packets depicted in FIGS.4A to 4D. The stylus detection unit 215 associates the packets from thestylus 100 with its configuration data CD (such as the stylus identifierSID of the stylus 100) and supplies them to the electronic apparatuscontrolling unit 300.

FIGS. 4A to 4D are views illustrating four operation modes M1 to M4 ofthe sensor controller 200 and the stylus 100 in the position inputtingmethod of the present invention.

FIG. 4A is a view illustrating the discovery mode M1. In the discoverymode M1, the sensor controller 200 and a stylus 100 mutually search fora communication partner. The sensor controller 200 transmits a discoverypacket D_UP including identification information of the sensorcontroller 200 in a slot after every predetermined period of time (forexample, in a slot after every eight time slots). The discover packetnotifies the stylus 100 of the presence of the sensor controller 200 andof the starting timing of a frame period. If the stylus 100 detects thediscovery packet D_UP, then it returns a discovery response packet D_DP.

FIG. 4B is a view illustrating the setting mode M2. In the setting modeM2, the sensor controller 200 uses a default communication channel(first communication channel) to set a second communication channel tobe used for communication between the sensor controller 200 and thestylus 100.

The sensor controller 200 sets a local identifier LID, which temporarilyidentifies the detected first stylus 101, and also sets a communicationchannel to be used for communication with the first stylus 101. Thesensor controller 200 notifies the local identifier LID and thecommunication channel to the stylus 101 using a configurationinformation request packet CD_UP and a channel change request packetCC_UP, respectively.

In the setting mode M2 (after the discovery mode M1 but before thestroke mode M3), the first stylus 101 initially transmits configurationdata CD including the stylus identifier SID using the defaultcommunication channel (the first communication channel).

Here, the communication between the sensor controller 200 and the stylus101 is carried out, for example, using a frequency time divisionmultiple access method. A communication channel in the case where afrequency time division multiple access is used is specified by thefrequency f and the time slot s. Accordingly, the channel change requestpacket CC_UP includes frequency allocation information that designates afrequency f and time slot allocation information that designates a timeslot s (see FIG. 6B). It is to be noted that the frequency allocationinformation may be included not in the channel change request packetCC_UP but in the discovery packet D_UP to be conveyed to the stylus 101.Similarly, the local identifier LID may be conveyed to the stylus 101,not in the configuration information request packet CD_UP, but in thediscovery packet D_UP.

FIG. 4C is a view illustrating the stroke mode M3. In the stroke modeM3, the stylus 100 and the sensor controller 200 perform transmissionand reception of operation state data OD, such as a pen pressure F,using the communication channel (the second communication channel) setup in the setting mode M2. In the stroke mode M3, transmission of theconfiguration data CD such as the stylus identifier SID, which does notvary depending on an operation state of the stylus, is omitted.

FIG. 4D is a view illustrating the hold mode M4. The hold mode M4 is astate in which the communication channel (the second communicationchannel) established in the setting mode M2 and the local identifier LIDallocated to the stylus 100 are (temporarily) maintained, for example,when the user lifts the stylus 100 from the sensor panel and holds it inthe air for some time before lowering it again to resume the handwritingoperation. The sensor controller 200 and the stylus 100, when detectingcommunication packets transmitted using the local identifier LID and thecommunication resource (the second communication channel) established inthe setting mode M2, determine to return to the stroke mode M andcontinue using the local identifier LID and the communication resource.On the other hand, when the sensor controller 200 and the stylus 100 donot detect communication packets transmitted using the local identifierLID and the communication resource set up in the setting mode M2 formore than a defined period of time, they release the local identifierLID and the communication resource and return to the discovery mode M1.

FIGS. 5A and 5B are views depicting a common format for various packets.A packet is configured including a synchronizing code Psync at thebeginning and a header HDR and a payload PL (FIG. 5A).

The synchronizing code Psync is a code used by the stylus 100 toestablish synchronization with the clock of the sensor controller 200.The synchronizing code Psync may be, for example, a PN code or a Barkercode selected by the sensor controller 200. The reception unit 113 ofthe stylus 100 detects a peak timing of a correlation value between thereception digital signal and the synchronizing code Psync to establishsynchronization with the clock of the sensor controller 200 (FIG. 5B).

The synchronizing code Psync is selected by the sensor controller 200 sothat the stylus 100 can identify the sensor controller 200 based on thesynchronizing code Psync. The code selected by the sensor controller 200is notified from the sensor controller 200 to the stylus 100 in adiscovery packet D_UP, to be described below (see FIG. 6A). Thesynchronizing code to be included in the synchronization code field ofthe discovery packet D_UP itself need not be the synchronizing codePsync, and may be a code prestored in each of the styluses 100 and thesensor controller 200 (e.g., synchronizing code Broadcast depicted inFIG. 6A). However, use of the synchronization code Psync for the purposeof identifying the sensor controller 200 is not always required, and insome embodiments the synchronizing code Broadcast may be used as asynchronizing code in all other packets in addition to the discoverypacket D_UP. The synchronizing code Broadcast is configured from a PNcode or a Barker code, similarly to the synchronizing code Psync.

The header HDR includes a local identifier LID and type information TYPEof the packet.

The local identifier LID is an identifier for uniquely identifying astylus 100, from among multiple styluses 100 that may be used with thesensor controller 200. The local identifier LID in a packet is used toidentify the particular stylus 100, which is to receive the packetaddressed to that stylus 100, or which has transmitted the packetincluding the local identifier LID.

The local identifier LID is information that represents an addressselected from among a plurality of addresses. For example, where thelocal identifier LID is formed of 3 bits, the local identifier LID canrepresent one address to be selected from among 2³=8 addresses. Thenumber of bits of the local identifier LID is preferably smaller thanthe number of bits of the stylus identifier SID. For example, preferablythe stylus identifier SID is information of 5 bits or more, while thelocal identifier LID is information of 4 bits or less. A bit number ofthe local identifier LID is preferably selected to be a numbersufficient for identify those styluses 100 which may be used alternatelyor substantially simultaneously on one sensor controller 200. Forexample, if 3 bits are used, it is possible to identify seven differentstyluses 100 while using one address as a Broadcast ID (meaning that allof the seven styluses 100 are addresses).

The first stylus 101 decides whether or not the local identifier LIDincluded in the reception digital signal and the local identifier LIDstored in its own communication setting table (see FIG. 2 ) coincidewith each other, to determine whether the packet is destined for thestylus itself (first stylus 101) or for a different stylus (e.g., secondstylus 102). A similar process to that performed regarding the firststylus 101 is performed regarding the second stylus 102.

The type information TYPE is a field used to distinguish the type ofpacket (see FIGS. 6A to 6D). The payload PL includes payload datacorresponding to the type of packet.

Here, packets to be transmitted from a stylus 100 and the sensorcontroller 200 are preferably transmitted in a state in which they arespread by a spread spectrum system such as, for example, a direct spreadspectrum system (DSSS). Spread codes used in this case may be prestoredin both of the stylus 100 and the sensor controller 200. By using aspread spectrum system in this manner, robust communication notsusceptible to noise becomes possible.

FIGS. 6A to 6D are views illustrating packets to be communicated in thefour operation modes M1 to M4 of the position inputting system 1.

(a) Packets to be Utilized in the Discovery Mode M1

The discovery packet D_UP is a packet (discovery packet) to be sent fromthe sensor controller 200 to an unspecified stylus 100 to detect a newstylus 100 and notify it of the presence of the sensor controller 200,and to supply a timing reference of a predetermined period T to thefirst stylus 101 or the second stylus 102 which has been detectedalready. A synchronizing code portion of the discovery packet D_UPincludes, instead of the synchronizing code Psync, the synchronizingcode Broadcast which can be received by any unspecified stylus 100. Thepayload of the discovery packet D_UP includes information including thesynchronizing code Psync that identifies the sensor controller 200, fromwhich the discovery packet D_UP is transmitted. As described above, anypacket other than the discovery packet D_UP may also use thesynchronizing code Broadcast as the synchronizing code; in such case thediscovery packet D_UP need not include information identifying thesynchronizing code Psync in the payload.

The discovery response packet D_DP is a packet (response packet)transmitted from the stylus 100 (e.g., first active capacitive stylus101), which has received the discovery packet D_UP, as a response to thesensor controller 200. Where the payload of the discovery packet D_UPincludes information that identifies the synchronizing code Psync, thesynchronizing code Psync is used as the synchronizing code of thediscovery response packet D_DP transmitted from the stylus.

(b) Packets to be Utilized in the Setting Mode M2

The configuration information request packet CD_UP is a packet by whichthe sensor controller 200 requests the stylus 100, which has respondedwith a discovery response packet D_DP, to transmit its configurationdata CD including the stylus identifier SID. Prior to transmitting theconfiguration information request packet CD_UP, the sensor controller200 performs a process to determine a local identifier LID to beassigned to the stylus 100, from which the discovery response packetD_DP is receives, and includes information regarding the assigned localidentifier LID in the payload PL of the configuration informationrequest packet CD_UP. In assigning the local identifier LID, the sensorcontroller 200 selects different local identifiers LID for differentstyluses 100, respectively, which are detected to be present on thesensor panel. As such, the local identifier LID is information that canbe used to distinguish one or more styluses 100 existing on the sensorpanel.

The configuration information transmission packet CD_DP is a packettransmitted from the stylus 100 and includes static configuration dataCD, such as the stylus identifier SID, which does not vary dependingupon an operation state of the stylus 100.

The channel change request packet CC_UP is a configuration packet (or asetting packet), which notifies a communication channel (secondcommunication channel) to the stylus 100, to which the sensor controller200 has assigned the local identifier LID, so that the stylus 100 cantransmit its operation state data OD on the notified communicationchannel. The channel change request packet CC_UP includes channel dataCHD indicative of the communication channel. In various exemplaryembodiments the communication channel is defined by a time slot s and/ora frequency f assigned to a particular stylus.

For example, specific information included in the channel data CHD mayinclude time slot designation information, which may be in the form ofan offset time period from a reference timing, wherein the referencetiming indicates the starting time of a frame. For example, in theexample of FIG. 7A hereinafter described, the reference timing is atransmission timing of a communication channel 700. A communicationchannel 701 is designated (defined) with the offset time period +1(relative to 700), which is used as the time slot designationinformation in this case. A communication channel 702 is designated withthe offset time period +2 (relative to 700), used as the time slotallocation information in this case. Meanwhile, frequency allocationinformation that designates any one of a plurality of frequenciesdetermined in advance can be included in the channel data CHD. Whiletypically the channel data CHD is transmitted in the setting mode M2,all or part (for example, only frequency allocation information) of thechannel data CHD may be included in the discovery packet D_UP. It is tobe noted that, as the time slot allocation information, an interval timeperiod, at which each of subsequent transmission time slots is repeatedafter the offset time period, may be indicated in addition to the offsettime period. For example, if the offset is set to +1 and the interval isdesignated as 2 time slots, then time slots s8 n+1, s8 n+3, s8 n+5, s8n+7, and so forth, may be designated.

(c) Packets to be Communicated in the Stroke Mode M3 (d) Packets to beCommunicated in the Hold Mode M4

The operation state request packet OD_UP is a packet that requests thestylus 100 designated by the local identifier LID to transmit operationstate data OD. The operation state request packet OD_UP does not includeany data in the payload part thereof.

The operation state transmission packet OD_DP is a packet transmittedfrom the stylus 100 and includes operation state data OD, which variesdepending upon an operation state of the stylus 100 such as the penpressure F data, a button operation state data, and so forth. Althoughthe operation state transmission packet OD_DP does not includeconfiguration data CD such as a stylus identifier SID, it may includethe local identifier LID as depicted in FIG. 6D. However, in someembodiments, since the sensor controller 200 can identify which stylus100 has transmitted the operation state transmission packet OD_DP basedon which communication channel the operation state transmission packetOD_DP is received, the local identifier LID need not be included in theoperation state transmission packet OD_DP. Further, the stylus maytransmit the state transmission packet OD_DP without having necessarilyreceived a request from the sensor controller in the operation staterequest packet OD_UP.

FIGS. 7A to 7D are views illustrating communication channels allocatedby the sensor controller 200. In FIGS. 7A to 7D, the axis of abscissaindicates time slots s0, s1, s2, . . . defined by a period T. A period Tis defined between the sensor controller 200 and a stylus 100, which isto communicate with the sensor controller 200, with reference to theclock of the sensor controller 200. A time slot s may be a transmissiontime period or a reception time period, or a combination of both atransmission time period and a reception time period. The axis ofordinate in FIGS. 7A to 7D indicates the frequency f, and frequenciesf0, f1, f2, . . . to be used for communication.

The communication channel is defined by a time domain (time slot s)and/or a frequency domain (frequency f) as described above and isallocated (designated) by the sensor controller 200.

In FIGS. 7A to 7D, the communication channel 700 indicated by slantedlines is a default communication channel (first communication channel)provided in order for the sensor controller 200 to search for a newstylus 100 in the discovery mode M1, or to perform communication withthe first stylus 101 detected in the discovery mode M1.

In FIGS. 7A to 7D, the communication channel 701 indicated as a whiteframe represents a communication channel (second communication channel)allocated to the detected first stylus 101, on which the sensorcontroller 200 and the first stylus 101 may communicate with each otherin the stroke mode M3 and in the hold mode M4.

In FIGS. 7A to 7D, the communication channel 702 indicated as a blackframe also depicts a communication channel (second communicationchannel) allocated to another detected stylus, such as the second stylus102, on which the sensor controller 200 and the second stylus 102 maycommunicate with each other in the stroke mode M3 and in the hold modeM4.

FIG. 7A depicts an example in which a communication channel is definedby time slots s. In this example, after every eight time slots s in aperiod (frame period) indicated by s8 n (n is 0 or a positive integer),a communication resource represented by the time slot s8 n is reservedas the default communication channel 700 (first communication channel)to be used, for example, in the discovery mode M1 by the sensorcontroller 200. The communication channel 700 is used for the sensorcontroller 200 to share, with the first stylus 101 and the second stylus102, starting time of the period T (frame period) where one periodincludes eight time slots of s0 to s7. Time slot s8 n+1 subsequent totime slot s8 n used by the sensor controller 200 is allocated to thefirst stylus 101 and forms the communication channel 701 (secondcommunication channel) for the first stylus 101. A further time slot s8n+2 is allocated to the second stylus 102 and forms the communicationchannel 702 (second communication channel) for the second stylus 102.

FIG. 7B depicts an example wherein a communication channel is defined bya frequency f. In the example, the communication channel of thefrequency f0 defines the default communication channel 700 (firstcommunication channel) to be used in the discovery mode M1 or in thesetting mode M2 by the sensor controller 200. The communication channel701 of frequency f1 (second communication channel) is assigned for thesensor controller 200 to communicate with the first stylus 101 in thestroke mode M3 or in the hold mode M4. The communication channel 702 offrequency f2 (another second communication channel) is assigned for thesensor controller 200 to communicate with the second stylus 102 in thestroke mode M3 or in the hold mode M4.

FIG. 7C depicts an example in which a communication channel is definedby a set of time slots s and a frequency f. In the example, thecommunication channel defined by the time slot s8 n is the defaultcommunication channel 700 (first communication channel), which is usedin the discovery mode M1 or in the setting mode M2 by the sensorcontroller 200. The communication channel 700 is set across the entirefrequency range f, on which the sensor controller 200 may transmit adiscovery packet D_UP to notify any styluses (e.g., the first stylus 101or the second stylus 102) of a starting timing of a period T. Thecommunication channel 701 (second communication channel) is configuredfor the sensor controller 200 to communicate with the first stylus 101in the stroke mode M3 or in the hold mode M4. The communication channel701 is defined by the frequency f1 and the time slot s8 n+1. Thecommunication channel 702 (second communication channel) is configuredfor the sensor controller 200 to communicate with the second stylus 102in the stroke mode M3 or in the hold mode M4. The communication channel702 is defined by the frequency f2 and the time slot s8 n+2.

FIG. 7D depicts another example in which a communication channel isdefined by a set of time slots s and a frequency f. The communicationchannel 700 indicated by slanted lines is defined by the time slot s8 n(n is 0 or a positive integer), similarly to that in FIG. 7A. Thecommunication channel 701 (second communication channel) is configuredfor the sensor controller 200 to communicate with the first stylus 101in the stroke mode M3 or in the hold mode M4. The communication channel701 is defined by the frequency f1 and the time slot s8 n+2. Thecommunication channel 702 (second communication channel) is configuredfor the sensor controller 200 to communicate with the second stylus 102in the stroke mode M3 or in the hold mode M4. The communication channel702 is defined by the frequency f2 and the time slot s8 n+2.

FIG. 8 is a view depicting a communication resource table CRTbl of thestylus detection unit 215. In an entry indicated by a row of the table,a local identifier LID, a communication channel (time slot s and/orfrequency f) assigned to a stylus 100, and configuration data CD such asa stylus identifier SID acquired in the setting mode M2 are stored.

When processing up to the setting mode M2 is completed between thesensor controller 200 and a stylus 100, all fields of the table entryfor the stylus 100 are filled.

The entry 801 includes information regarding the first stylus 101. Ifthe stylus detection unit 215 receives an operation state transmissionpacket OD_DP from the first stylus 101, then it decides, on the basis ofthe value of the local identifier LID included in the operation statetransmission packet OD_DP or the communication channel 701 on which theoperation state transmission packet OD_DP is received, that the positionindicated by transmission of the operation state transmission packetOD_DP has originated from the first stylus 101.

The entry 802 includes information regarding the second stylus 102. Ifthe stylus detection unit 215 receives an operation state transmissionpacket OD_DP from the second stylus 102, then it decides, on the basisof the value of the local identifier LID included in the operation statetransmission packet OD_DP or the communication channel 702 on which theoperation state transmission packet OD_DP is received, that the positionindicated by transmission of the operation state transmission packetOD_DP has originated from the second stylus 102.

Each entry of the communication resource table CRTbl is deleted (purged)when the sensor controller 200 and the stylus 100 return from the holdmode M4 to the discovery mode M1.

FIG. 9 is an operation flow chart of the sensor controller 200 (stylusdetection unit 215).

<Discovery Mode M1: Sensor Controller 200>

The sensor controller 200 starts its operation in the discovery mode M1.At step S911, the sensor controller 200 uses the communication channel700 (first communication channel) in the time slot s8 n (n is 0 or apositive integer) depicted in FIG. 7A or 7D to transmit a discoverypacket D_UP. At step S913, transmission of the discovery packet D_UP isrepeated according to a defined period T (for example, after every eighttime slots) until a discovery response packet D_DP is received at stepS913.

<Setting Mode M2: Sensor Controller 200>

When the sensor controller 200 receives a discovery response packet D_DPfrom a stylus 100 at step S913, then the operation mode of the sensorcontroller 200 changes to the setting mode M2. It should be noted that,even after the mode changes to the setting mode M2 or to a subsequentmode, transmission of the discovery packet D_UP is repeated in order todetect a different new stylus 100.

At step S921, the sensor controller 200 assigns a local identifier LIDfor identifying the detected stylus 100. Then, the sensor controller 200sends to the stylus 100 a configuration information request packet CD_UPincluding the assigned local identifier LID.

At step S923, the sensor controller 200 receives a configurationinformation transmission packet CD_DP from the stylus 100 (YES at S923)and detects configuration data CD, such as a stylus identifier SID,included in the configuration information transmission packet CD_DP.

At step s925, the sensor controller 200 determines a communicationchannel (second communication channel) to be used for subsequentcommunication with the stylus 100. For example, according to the exampleof FIG. 7D, the sensor controller 200 allocates (designates) thecommunication channel 701 defined by the time slot s8 n+1 (n is 0 or apositive integer) and the frequency f1 to the first stylus 101. Thesensor controller 200 registers a corresponding relationship between theallocated communication channel 701 and the configuration data CD in thecommunication resource table CRTbl of FIG. 8 .

At step S927, the sensor controller 200 transmits a channel changerequest packet CC_UP to the stylus 100, to notify the stylus 100 of theset of the time slot s8 n+1 (n is 0 or a positive integer) and thefrequency f1 that are determined for the stylus 100, wherein the setdefines the communication channel 701 (second communication channel)allocated to the stylus 100 for use in communication in the stroke modeM3.

It is to be noted that the sensor controller 200 may determine a portion(e.g., a frequency) of a communication channel and a local identifierLID prior to transmission of the discovery packet D_UP. The sensorcontroller 200 may then include the determined information (e.g., thefrequency and the LID) in the discovery packet D_UP. This makes itpossible for the stylus 100 to quickly obtain the local identifier LIDallocated to the stylus 100 and a portion (e.g., a frequency) of thecommunication channel in the discovery packet D_UP, without having towait for the configuration information request packet CD_UP and thechannel change request packet CC_UP.

<Stroke Mode M3: Sensor Controller 200>

Starting with step S931, a process for repeatedly performing receptionof am operation state transmission packet OD_DP is performed.

First, at step S931, the sensor controller 200 requests a stylus orstyluses, which are already detected (or linked/connected) and thus areregistered in the communication resource table CRTbl, to transmit anoperation state transmission packet OD_DP. This request may be performedby the sensor controller 200 explicitly transmitting, to the stylus 100,an operation state request packet OD_UP, or by the sensor controllermerely transmitting, to the stylus 100, a discovery packet D_UP in aparticular time slot s. For example, in the latter case, the sensorcontroller 200 transmits the discovery packet D_UP in the time slot s8 n(n is 0 or a positive integer) to implicitly expect the operation statetransmission packet OD_DP to be transmitted in the second communicationchannel (e.g., in the time slot s8 n+1 following the time slot s8 n, andin the frequency f1).

The stylus detection unit 215 (see FIG. 3 ) of the sensor controller200, which receives the operation state transmission packet OD_DP in thesecond communication channel, derives a coordinate position of thestylus 100 based on position information Pos supplied thereto from thereception unit 213. The stylus detection unit 215 also reads out, fromthe communication resource table CRTbl, configuration data CD thatcorresponds to the communication channel in which the operation statetransmission packet OD_DP is received (step S934). Then, the stylusdetection unit 215 supplies the derived coordinate position and thestylus identifier SID included in the configuration data CD, in anassociated relationship with each other, to the electronic apparatuscontrolling unit 300. It is to be noted that, at this time, operationstate data OD may naturally be extracted from the operation statetransmission packet OD_DP and supplied to the electronic apparatuscontrolling unit 300 together with the coordinate position.

At step S939, the sensor controller 200 initializes the value of acontinuous non-reception counter and repeats the process of step S931 tocontinue the operation in the stroke mode M3.

In the stroke mode M3, while the user continues to operate the stylus100 on the sensor panel after the user first lowers the stylus 100 ontothe sensor panel until the user lifts the stylus 100 up from the sensorpanel, the stylus 100 can be identified based on the communicationchannel assigned to the stylus 100 or based on the local identifier LIDassigned to the communication channel. Therefore, transmission of thestylus identifier SID having the full length of 48 bits or 64 bits canbe omitted.

<Hold Mode M4: Sensor Controller 200>

On the other hand, if an operation state transmission packet OD_DP isnot received at step S933, then the sensor controller 200 detects atstep S945 how many times (e.g., periods) an operation state transmissionpacket OD_DP has not been received consecutively. If packets are notreceived consecutively from the stylus 100, which was once in the strokemode M3, then there is the possibility that the user has temporarilylifted the stylus 100 from the panel and is holding it in the air untilthe user again lowers the stylus 100 toward the panel. Thus, when anoperation state transmission packet OD_DP is not received consecutivelyN or less number of times, the sensor controller 200 maintains thecommunication channel (second communication channel) used forcommunication with the stylus 100.

For example, the sensor controller 200 increments the continuousnon-reception counter at step S947 and waits to receive an operationstate transmission packet OD_DP while maintaining the secondcommunication channel. If an operation state transmission packet OD_DPis received in this state, then the sensor controller 200 receives theoperation state data OD using the same second communication channel,which the sensor controller 200 has used when the stylus was previouslyin the stroke mode M3, and supplies the operation state data OD togetherwith the configuration data CD associated with the second communicationchannel to the electronic apparatus controlling unit 300.

On the other hand, if it is detected that an operation statetransmission packet OD_DP is not received consecutively for a number oftimes that exceeds N times at step S945, then the sensor controller 200determines that the user has not lifted the stylus 100 merelytemporarily but rather has stopped the use of the stylus 100 altogether.In this case, the sensor controller 200 deletes the pertaining entryfrom the communication resource table CRTbl, releases the secondcommunication channel and the local identifier LID (step S949), and thenreturns to the discovery mode M1, in which communication is performedusing the first communication channel.

FIG. 10 is an operation flow diagram of a stylus 100 (communicationcontrolling unit 120).

<Discovery mode M1: Stylus 100>

The stylus 100 starts its operation in the discovery mode M1. At stepS1011, the stylus 100 performs detection of a discovery packet D_UP in adefault communication channel (first communication channel). If adiscovery packet D_UP is not received (No at S1011), then the stylus 100repeats detection of a discovery packet D_UP in a predetermined cycle(period). If a discovery packet D_UP is received at step S1011, then thestylus 100 acquires a synchronizing code Psync from the discovery packetD_UP and sends out a discovery response packet D_DP. The stylus copiesthe successfully acquired synchronizing code Psync into the discoveryresponse packet D_DP. If the stylus cannot acquire the synchronizingcode Psync from the discovery packet D_UP, the stylus includes thesynchronizing code Broadcast included in the discovery packet D_UP inthe discovery response packet D_DP.

<Setting Mode M2: Stylus 100>

At step S1021, the stylus 100 acquires a local identifier LID includedin the configuration information request packet CD_UP (or in thediscovery packet D_UP) and sets the local identifier LID in thecommunication setting table depicted in FIG. 2 . Further, the stylus 100sets a code train PN indicative of the synchronizing code Psync (or thesynchronizing code Broadcast) acquired from the discovery packet D_UP ina correlator of the reception unit 113.

At step S1023, the stylus 100 transmits a configuration informationtransmission packet CD_DP, which includes configuration data CD such asthe stylus identifier SID. Since, typically, the operation in thesetting mode M2 is performed only once upon initiation of eachcommunication, even when the stylus identifier SID is as long as 48 bitsor 64 bits or when configuration data CD includes additional informationsuch as a vendor ID or a brush type, the amount of communicationresources needed for the transmission of the configuration data CD isreduced as compared to the communication method disclosed in PatentDocument 1 described above. It should be noted that, in the initialcommunication of the stylus identifier SID represented by a large numberof bits, the configuration information transmission packet CD_DP may betransmitted in a divided manner using a plurality of time slots.

At step S1027, the stylus 100 receives a channel change request packetCC_UP and acquires a communication channel (second communicationchannel) designated by the channel change request packet CC_UP. It is tobe noted that, where a portion of the communication channel has beennotified in a discovery packet D_UP, the stylus 100 combines thealready-received portion of the communication channel with the remainingportion designated by the channel change request packet CC_UP to acquirethe communication channel (second communication channel). The stylus 100sets information regarding the acquired communication channel (frequencyf (e.g., f1) and time slots s (e.g., s8 n+1)) in the communicationsetting table depicted in FIG. 2 , and configures the oscillation unit111 and the transmission-reception switching unit 104 based on theinformation, to thereby use the communication channel (secondcommunication channel) for communication in the stroke mode M3.

<Stroke Mode M3: Stylus 100>

At step S1031, the stylus 100 decides whether the present point of timeis a transmission timing for an operation state transmission packetOD_DP. This decision may be prompted by receipt of an operation staterequest packet OD_UP transmitted explicitly from the sensor controller200, or by receipt of a discovery packet D_UP transmitted in the timeslot s8 n from the sensor controller 200, which implicitly designatesthe subsequent time slot s8 n+1 as the time slot in which the stylus 100is to transmit the operation state transmission packet OD_DP.

If the result of the decision at step S1031 is YES, then the stylus 100transmits the operation state transmission packet OD_DP in, for example,the second communication channel (frequency f1 and time slot s8 n+1)depicted in FIG. 7D. At step S1035, the stylus 100 initializes the valueof the continuous non-reception counter and returns to the process ofstep S1031. Thus, the stylus 100 continues the operation in the strokemode M3 until it is lifted from the panel. Typically, during a period oftime after the stylus 100 has been placed on the panel until the stylus100 is lifted up, an operation state request packet OD_UP is received inthe second communication channel (or a discovery packet D_UP is receivedin the first communication channel), and the operation statetransmission packet OD_DP continues to be transmitted.

<Hold Mode M4: Stylus 100>

If an operation state request packet OD_UP (or a discovery packet D_UP)is not received at step S1031, then the stylus 100 detects at step S1041how many times (how long) an operation state request packet OD_UP (or adiscovery packet D_UP) has not been received consecutively.

If an operation state request packet OD_UP (or a discovery packet D_UP)has not been received consecutively N or less number of times, then thestylus 100 determines that there remains the possibility that the usermay resume use of the stylus 100, after a temporally removal from thepanel, by lowering the stylus 100 onto the sensor panel to resume itscommunication with the sensor controller 200. Accordingly, within thisperiod of time, while the continuous non-reception counter issuccessively incremented at step S1043, the second communication channeland the local identifier LID to be used for communication with thesensor controller 200 are maintained. In the hold mode M4, the stylus100 uses the second communication channel designated in thecommunication setting table to continue to try to receive an operationstate request packet OD_UP, and returns to the stroke mode M3immediately if a new operation state request packet is received.

On the other hand, if a packet is not received from the sensorcontroller 200 for a number of times that exceeds N times at step S945,then the stylus 100 determines that use of the stylus 100 is ceased, andreleases the second communication channel and the local identifier LIDset in the communication setting table. The stylus 100 returns to thediscovery mode M1, in which the first communication channel is utilized.

Operation Example 1: Where the First Stylus 101 Repeats Moving into andOut of the Detection Range

FIG. 11 is a view illustrating operation of the position inputtingsystem 1 when the first stylus 101 repeats moving into and out of thedetection range of the sensor controller 200.

The three rows in the upper portion of FIG. 11 (f0, f1, f2) indicatefrequencies f of the communication channels to be utilized. Referencecharacters s0 to s610 in the horizontal direction denote time slots s.

Similarly as in FIGS. 7A to 7D, a communication channel indicated byslanted lines indicates a default communication channel (firstcommunication channel) to be used to transmit a discovery packet D_UP orthe like from the sensor controller 200 to an unspecified stylus 100. Acommunication channel indicated as a white frame (white circle)indicates a communication channel (second communication channel) used bythe first stylus 101 to transmit operation state data OD in the strokemode M3. The axis of abscissa denoted by “mode 101” indicates operationmodes in communication between the first stylus 101 and the sensorcontroller 200. The bottom portion in FIG. 11 indicates a packetsequence between the first stylus 101 and the sensor controller 200.

The discovery mode M1 is executed from the time slot s0 through the timeslot s201.

While the discovery mode M1 is executed, the sensor controller 200continues to send out a discovery packet D_UP using the firstcommunication channel, indicated by slanted lines, in a predeterminedperiod (e.g., every eight time slots s, such as time slots s0, s8, s200,and s8 n (n is 0 or a positive integer)).

When the first stylus 101 moves closer to the sensor controller 200 andreturns a discovery response packet D_DP in the time slot s201, then theoperation of the position inputting system 1 formed of the first stylus101 and the sensor controller 200 transitions from the discovery mode M1to the setting mode M2.

Within a period from the time slot s208 to the time slot s279, thesetting mode M2 is executed.

During the setting mode M2 for the first (initial) time, the firststylus 101 sends out a configuration information transmission packetCD_DP including configuration data CD, which does not vary in responseto an operation state of the first stylus 101, such as a stylusidentifier SID of 48 bits or 64 bits. Meanwhile, the sensor controller200 transmits a configuration information request packet CD_UP includingthe local identifier LID assigned to the first stylus 101 and a channelchange request packet CC_UP including channel data CHD indicative of thesecond communication channel.

The time from the time slot s280 to the time slot s407 is a time periodwithin which the user slidingly moves the first stylus 101 on the panel.During the sliding movement, the stroke mode M3 is executed as theoperation mode of the position inputting system 1 formed of the firststylus 101 and the sensor controller 200.

In the example of FIG. 11 , the operation state data OD, which variesdepending upon an operation state of the first stylus 101 such as thepen pressure F and ON-OFF states of the buttons, is transmittedrepeatedly in the second communication channel. The second communicationchannel may be defined, for example, by the set of the time slots s8n+1, which are subsequent to the time slots s8 n in which the discoverypacket D_UP is received from the sensor controller 200, and thefrequency f1.

Within the period from the time slot s408 to the time slot s599preceding the time slot s600, the hold mode M4 is executed.

While the sensor controller 200 waits to receive an operation statetransmission packet OD_DP in the second communication channel, if thefirst stylus 101 is removed from the panel and cannot detect(communicate with) the sensor controller 200, the sensor controller 200does not receive an operation state transmission packet OD_DP.

Starting at the time slot s600, if the first stylus 101 is againdetected in the time slot s601 (or in the time slot s600), the strokemode M3 is again executed as the operation mode of the positioninputting system 1. The first stylus 101 again transmits to the sensorcontroller 200 operation state data OD in an operation statetransmission packet OD_DP, which includes the local identifier LID, inthe second communication channel defined by the set of the frequency f1and the time slots s8 n+1. As described above, the local identifier LIDneed not be included in the operation state transmission packet OD_DP insome embodiments.

The sensor controller 200 identifies a stylus, from which operationstate data OD is transmitted, based on the communication channelallocated to the first stylus 101 (or the local identifier LIDassociated with the communication channel). Therefore, the first stylus101 can omit sending the stylus identifier SID during the stroke modeM3.

In exemplary embodiments, the sensor controller 200 is configured toacquire the stylus identifier SID of the stylus 101 in the setting modeM2 and to manage the acquired stylus identifier SID in association withthe communication channel assigned to the stylus 101 in thecommunication resource table CRTbl. Therefore, even if the stylusidentifier SID is not supplied in each of subsequent communicationinstances, the sensor controller 200 can output the received operationstate data OD in association with the stylus identifier SID.

In the hold mode M4, the sensor controller 200 waits (stands by) for adefined period of time, following the stroke mode M3, while maintainingthe communication resource and the local identifier LID for the stylus100. Therefore, when the stylus 100 repeats moving into and out of thedetection range of the sensor controller 200, the number of times thestylus identifier SID needs to be sent or the number of bits needed tosend the stylus identifier SID can be reduced.

Operation Example 2: Where a Plurality of Styluses 100 are AlternatelyUsed

FIG. 12 is a view depicting operation of the position inputting system 1when the first stylus 101 and the second stylus 102 alternately moveinto and out of the detection range of the sensor controller 200.Description of elements similar to those of FIG. 11 are omitted to avoidredundancy.

A communication channel indicated as a black frame (or black circle) inFIG. 12 indicates a communication channel (second communication channel)used for packet transmission from the second stylus 102. The axis ofabscissa indicated by “mode 102” indicates an operation modes of theposition inputting system formed of the second stylus 102 and thecontroller 200.

During the period from the time slot s800 until the time slot s2001, theuser, for example, sets aside the first stylus 101 that the user haspreviously used, and instead uses the second stylus 102 in place of thefirst stylus 101. Within this time period, the position inputting systemformed of the first stylus 101 and the sensor controller 200 operates inthe hold mode M4.

The time slot s801 is a timing at which, for example, the user lowersthe second stylus 102 to the panel. In the time slot s801, the secondstylus 102 sends a reply to a discovery packet D_UP transmitted in adefined period from the sensor controller 200 using a defaultcommunication channel (communication channel of the frequency f0).

During the time period from the time slot s808 to the time slot s839,the second stylus 102 and the sensor controller 200 exchangeconfiguration data CD in the setting mode M2. The sensor controller 200refers to the communication resource table CRTbl to determine that thefirst stylus 101 is in the hold mode M4, that the local identifier LIDassigned to the first stylus 101 is 0b001, and that the secondcommunication channel assigned to the first stylus 101 is thecommunication channel defined by the time slot s8 n+1 and the frequencyf1. Then, the sensor controller 200 allocates to the second stylus 102 alocal identifier LID (e.g., 0b0101) and a second communication channel(e.g., the time slot s8 n+2 and the frequency f2), which are differentfrom the resources allocated to the first stylus 101, and notifies theallocated local identifier LID and the second communication channel tothe second stylus 102. In the communication resource table CRTbl, anentry for the second stylus 102 is generated and stored.

During the time slots from the time slot s840 to the time slot s1007,the second stylus 102 and the sensor controller 200 operate in thestroke mode M3. During this time period, the communication resource(second communication channel) for the first stylus 101 is maintained tosupport (possible) subsequent return of the first stylus 101 onto thesensor panel.

In the time slot s1008, if the second stylus 102 is, for example,removed from the sensor panel and thus becomes unable to communicate inthe second communication channel, then the second stylus 102 and thesensor controller 200 transitions to the hold mode M4. The communicationresources which utilize the frequency f2 (as assigned to the secondstylus 102) are maintained in the communication resource table CRTbl.

In the time period starting from the time slot s2000, the first stylus101 has returned from the hold mode M4 to the stroke mode M3. Since thecommunication channel of the frequency f1 has been maintained, the firststylus 101 need not perform operation of the discovery mode M1 or thesetting mode M2. Therefore, the first stylus 101 may resume itsoperation in the stroke mode M3 quickly, without having to transmit itsstylus identifier SID represented by a large number of bits such as 48bits or 64 bits.

Thus, even when a plurality of styluses 100 are alternately used on thesensor panel, the number of times the stylus identifier SID needs to betransmitted from each of the styluses 100 can be reduced and theprocessing sequence required to set up the communication resource foreach of the styluses 100 can be omitted.

As described above, with the method of the present invention, the sensorcontroller 200 can identify the first stylus 101 based on the first timeslot, which is designated (assigned) by the channel change requestpacket CC_UP. Accordingly, even if a stylus identifier SID is notattached to operation state data OD, the sensor controller 200 canrecognize that the operation state data OD has been transmitted from thefirst stylus 101 (based on the fact that the operation state data OD isreceived in the first time slot). Accordingly, the first stylus 101 canomit transmission of the stylus identifier SID when it transmitsoperation state data OD.

Further, with the method according to the present embodiment, the sensorcontroller 200 can acquire a stylus identifier SID from the first stylus101 and thereafter manage the acquired stylus identifier SID inassociation with the communication channel used to communicate with thefirst stylus 101 in the communication resource table CRTbl. Accordingly,even if the stylus identifier SID is not added to operation state dataOD, the sensor controller 200 can output the received operation statedata OD in association with the stylus identifier SID of the firststylus 101 to the electronic apparatus controlling unit 300.

Furthermore, with the method according to the present embodiment,subsequent to the stroke mode M3 in which a stylus 100 and the sensorcontroller 200 successively communicate operation state data OD, thehold mode M4 is provided in which they both stand by for a definedperiod of time while maintaining the assigned communication resource andthe local identifier LID. Accordingly, when the first stylus 101repeatedly moves into and out of the detection rage of the sensorcontroller 200 or when the first stylus 101 and the second stylus 102are alternately used, the stroke mode M3 can be quickly restored toresume communication of operation state data OD without requiring theprocessing in the setting mode M2 or the like. As a result, the numberof times a stylus identifier SID needs to be sent out can be reduced.

The present invention is not limited to the embodiments described aboveand can be carried out in various forms without departing from the scopeof the present disclosure.

For example, the sensor controller 200 in the embodiment described aboveretains a stylus identifier SID (of the stylus 100) in the communicationresource table CRTbl until the second communication channel and thelocal identifier LID assigned to the stylus 100 are released at stepS949 depicted in FIG. 9 . However, the sensor controller 200 may deletethe stylus identifier SID from the communication resource table CRTb1upon expiration of a defined period of time after the sensor controller200 stops receiving an operation state transmission packet OD_DP fromthe stylus 100. In the following, this modification is described indetail with reference to FIG. 13 .

FIG. 13 depicts a modification to the operation flow chart of the sensorcontroller 200 (stylus detection unit 215). The present modification isdifferent from the example depicted in FIG. 9 in regard to processing inthe stroke mode M3 and the hold mode M4, and though not depicted in FIG.13 , processing in the discovery mode M1 and the setting mode M2 is thesame as that in the example of FIG. 9 . In the following, description isgiven primarily of differences between the present modification and theexample of FIG. 9 .

The sensor controller 200 in the present modification determines, whenan operation state transmission packet OD_DP is not received at stepS933, whether or not the consecutive non-reception counter is equal to aconstant value N1 (step S941). The constant value N1 is a number smallerthan the constant value N used in the decision at step S945. If thesensor controller 200 determines at step S941 that the consecutivenon-reception counter is not equal to the constant value N, then itadvances to step S945 and performs processing similar to that in theexample of FIG. 9 . On the other hand, if the sensor controller 200determines that the consecutive non-reception counter is equal to theconstant value N, then it deletes the stylus identifier SID from therelevant record entry in the communication resource table CRTbl (stepS943). Thereafter, the processing advances to step S945, and the sensorcontroller performs processing similar to that in the example of FIG. 9. According this modification, upon expiration of a defined period oftime after it is detected that an operation state transmission packetOD_DP is not received, the stylus identifier SID is deleted from thecommunication resource table CRTbl.

In step S934 in the stroke mode M3, the sensor controller 200 attemptsto read out configuration data CD including the stylus identifier SIDfrom the communication resource table CRTbl and, in step S935,determines whether it has failed in reading out the stylus identifierSID. If the stylus identifier SID has been deleted from the relevantrecord in the communication resource table CRTbl at step S943, then thedecision result at step S935 would be YES. If the sensor controller 200determines at step S935 that it has not failed to read out the stylusidentifier SID, then it supplies the coordinate position derived at stepS934 and the stylus identifier SID read out from the communicationresource table CRTbl in an associated relationship with each other tothe electronic apparatus controlling unit 300 (not depicted).Thereafter, the sensor controller 200 advances to step S939 and performssubsequent processing similar to that of the example in FIG. 9 . On theother hand, if the sensor controller 200 determines that it has failedto read out the stylus identifier SID at step s935, then in step S936 itre-sends the configuration information request packet CD_UP, which hasbeen transmitted at step S921 of FIG. 9 . Then, the sensor controller200 determines whether a configuration information transmission packetCD_DP is received in response from the stylus 100 (step S937). If thesensor controller 200 determines that a configuration informationtransmission packet CD_DP is received (YES at S937), then it extractsconfiguration data CD such as a stylus identifier SID from the receivedconfiguration information transmission packet CD_DP and registers theconfiguration data CD in the corresponding record in the communicationresource table CRTbl (step S937). As a result, the communicationresource and the stylus identifier SID are again stored in an associatedrelationship with each other in the sensor controller 200. Thereafter,the sensor controller 200 supplies the coordinate position derived atstep S934 and the stylus identifier SID newly registered in thecommunication resource table CRTbl in an associated relationship witheach other to the electronic apparatus controlling unit 300 (notdepicted). Thereafter, the sensor controller 200 advances to step S939,and performs subsequent processing similar to that of the example inFIG. 9 . If the sensor controller 200 determines that a configurationinformation transmission packet CD_DP is not received at step S937, theprocessing advances to step S941, and performs subsequent processingsimilar to that of the example in FIG. 9 .

As described above, with the sensor controller 200 according to thepresent modification, when a fixed period of time elapses after it isdetected that an operation state transmission packet OD_DP is notreceived, the stylus identifier SID is deleted from the communicationresource table CRTbl. Therefore, a portion of the storage area of thesensor controller 200 occupied by the communication resource table CRTblcan be released at an earlier timing than that in the previousembodiments. Further, if the stylus identifier SID is required again,then the stylus identifier SID can be received again from the stylus100. Therefore, the sensor controller 200 according to the presentmodification also can readily perform supply of data (coordinateposition and stylus identifier SID) to the electronic apparatuscontrolling unit 300.

1. An active stylus, comprising: a receiver configured to detect acontrol signal transmitted from a sensor panel; a transmitter configuredto transmit a stylus signal to the sensor panel; and an integratedcircuit configured to selectively enter different operation modesincluding: a first mode in which detection of the control signal isrepeatedly attempted; a second mode in which, after the control signalis detected, a communication setting for transmitting the stylus signalis configured and the stylus signal is transmitted according to thecommunication setting; and a third mode in which, after the controlsignal ceases to be detected, the communication setting is maintainedfor a defined period of time.
 2. The active stylus of claim 1, wherein,in the third mode, the stylus signal is repeatedly transmitted accordingto the maintained communication setting.
 3. The active stylus of claim1, wherein, in the second mode, the stylus signal is repeatedlytransmitted according to the communication setting as long as the activestylus traverses over a surface of the sensor panel.
 4. The activestylus of claim 1, wherein, the communication setting includes a localID (LID) allocated to the active stylus, and the LID is released afterthe defined period of time in response to not detecting the controlsignal for the defined period of time.
 5. The active stylus of claim 1,wherein, the integrated circuit returns to the first mode from the thirdmode in response to not detecting the control signal for the definedperiod of time; and the integrated circuit returns to the second modefrom the third mode in response to detecting the control signal in thedefined period of time.
 6. The active stylus of claim 5, wherein theintegrated circuit, in response to detecting the control signal in thedefined period of time, returns to the second mode from the third modewhile maintaining the communication setting.
 7. A method implemented byan active stylus, comprising: detecting a control signal transmittedfrom a sensor panel; transmitting a stylus signal to the sensor panel;and selectively entering different operation modes including: a firstmode in which detection of the control signal is repeatedly attempted; asecond mode in which, after the control signal is detected, acommunication setting for transmitting the stylus signal is configuredand the stylus signal is transmitted according to the communicationsetting; and a third mode in which, after the control signal ceases tobe detected, the communication setting is maintained for a definedperiod of time.
 8. The method of claim 7, wherein, in the third mode,the stylus signal is repeatedly transmitted according to the maintainedcommunication setting.
 9. The method of claim 7, wherein, in the secondmode, the stylus signal is repeatedly transmitted according to thecommunication setting as long as the active stylus traverses over asurface of the sensor panel.
 10. The method of claim 7, wherein, thecommunication setting includes a local ID (LID) allocated to the activestylus, and the method includes releasing the LID after the definedperiod of time in response to not detecting the control signal for thedefined period of time.
 11. The method of claim 7, comprising: returningto the first mode from the third mode in response to not detecting thecontrol signal for the defined period of time; and returning to thesecond mode from the third mode in response to detecting the controlsignal in the defined period of time.
 12. The method of claim 11,comprising: in response to detecting the control signal in the definedperiod of time, returning to the second mode from the third mode whilemaintaining the communication setting.
 13. An integrated circuitconfigured to control operation of an active stylus, the integratedcircuit comprising: reception circuitry configured to detect a controlsignal transmitted from a sensor panel; transmission circuitryconfigured to transmit, via an electrode of the active stylus, a stylussignal to the sensor panel; and processing circuitry configured toselectively enter different operation modes of the active stylusincluding: a first mode in which detection of the control signal fromthe sensor panel is repeatedly attempted; a second mode in which, afterthe control signal is detected, a communication setting for transmittingthe stylus signal is configured and the stylus signal is transmittedfrom the active stylus according to the communication setting; and athird mode in which, after the control signal ceases to be detected, thecommunication setting is maintained for a defined period of time. 14.The integrated circuit of claim 13, wherein, in the third mode, thestylus signal is repeatedly transmitted according to the maintainedcommunication setting.
 15. The integrated circuit of claim 13, wherein,in the second mode, the stylus signal is repeatedly transmittedaccording to the communication setting as long as the active stylustraverses over a surface of the sensor panel.
 16. The integrated circuitof claim 13, wherein, the communication setting includes a local ID(LID) allocated to the active stylus, and the processing circuitryreleases the LID after the defined period of time in response to notdetecting the control signal for the defined period of time.
 17. Theintegrated circuit of claim 13, wherein, the processing circuitryreturns to the first mode from the third mode in response to notdetecting the control signal for the defined period of time; and theprocessing circuitry returns to the second mode from the third mode inresponse to detecting the control signal in the defined period of time.18. The integrated circuit of claim 17, wherein the processingcircuitry, in response to detecting the control signal in the definedperiod of time, returns to the second mode from the third mode whilemaintaining the communication setting.